JPH0412824A - Blow molding of exterior trim of automobile - Google Patents

Abstract

PURPOSE:To enable the beautiful appearance of a product to be obtained even if it is coated without polishing by a method in which the film composed of the material compatible with the synthetic resin for blow molding is heated by an infrared ray heater, and is vacuum-sucked on the mold for blow molding, and then a parison is fed therein and is molded. CONSTITUTION:The sucking hole 6 for vacuum-suction is provided in one mold 4A of a pair of molds 4A, 4B. A long film 16 is composed of the synthetic resin fully compatible with the synthetic resin which constitutes a parison 15 and is spread oppositely to the mold 4A. A far infrared ray heater 20 is held at the position opposite to the mold 4A through the film 16, and is retracted to the position which does not disturb blow molding by a cylinder or is restored. The film 16 is spread, while it is brought in contact with the mold 4A, and then it is heated and softened with the heater 20 and is vacuum-sucked by a vacuum-sucking hole 6. The heater 20 is retracted, and the parison 15 is caused to hang down. The molds 4A, 4B are closed, and blow molding is carried out. The obtained molded object has smooth surface, and obtains beautiful appearance even if it is coated without polishing.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for blow molding exterior parts of vehicles using synthetic resin materials, and particularly relates to a method for blow molding vehicle exterior parts using synthetic resin materials. This invention relates to a blow molding method that is improved so that a product with a good appearance can be obtained.

[Conventional technology]

When exterior parts for vehicles (for example, spoilers) are constructed from synthetic resin materials, hollow structures are often used to make them durable and lightweight.

FIG. 2 is a sectional view of a conventional spoiler 1 made of synthetic resin.

The outline of a spoiler is a fluid-dynamically complex curved surface, but when viewed conceptually, the top surface is a curved surface that tends to be convex, the side surfaces are convex curved surfaces, and the bottom surface is a curved surface that is close to a flat surface. There is.

The above-mentioned side surfaces refer to the four circumferences in the horizontal direction, regardless of the direction in which the vehicle is traveling. Therefore, both the front end surface and the rear end surface in the traveling direction of the vehicle are the side surfaces referred to here.

This conventional spoiler 1 is constructed by joining an upper surface plate 1a and a lower surface plate 1b which are injection molded from a synthetic resin material.

The plane P-P is a joint surface between the upper surface plate 1a and the lower surface plate 1b, and also corresponds to a parting line of a mold when molding each of the upper surface plate 1a and the lower surface plate 1b.

Joint portion 2 of upper surface plate 1a and lower surface plate 1b in this conventional example
Since a+2b is the most visible part when mounted on a car,
Finishing must be done to remove any unevenness at the joint.

Therefore, the number of man-hours required for processing is large, and the manufacturing cost is relatively high.

A spoiler 3 as shown in FIG. 3 is also known for moving the joint to a position where it is not visually noticeable.

The spoiler 3 of this conventional example is constructed by joining together an upper surface plate 3a that is convex upwardly and laterally and concave downwardly, and a lower surface plate 3b that is substantially flat.

3a-1 is a convex curved surface at the front end of the top plate 3a, and 3a-2 is a
The convex curved surface at the rear end of the top plate 3a, 3a-3, is the downwardly concave inner surface of the top plate 3a.

3a-4 is an opening of the concave surface 3a-3.

The lower plate 3b is fitted and joined so as to cover the opening 3a-4.

According to this conventional example (FIG. 3), the joint portion 2c.

2d is located on the lower side of the overall shape of the spoiler 3 and is an inconspicuous location when mounted on a vehicle, so the finishing of the joint does not need to be done very carefully.

In the conventional example shown in Fig. 3, compared to the conventional example shown in Fig. 2, the joint between the top plate and the bottom plate is located in a less conspicuous location, so fewer man-hours are required for finishing the joint. Are better.

However, when injection molding the top plate 3a of the spoiler 3 of the conventional example shown in FIG. 3 from a synthetic resin material, creating an undercut in the opening 3a-4 would complicate the mold configuration and increase equipment costs. In addition to the high production cost, the number of man-hours required for production is high, making the production cost relatively high.

Therefore, when attempting to simplify the mold configuration by not forming an undercut in the opening 3a-4, a thick portion 3a-5 is formed inside the front end convex curved surface 3a-1, and a rear end convex curved surface 3a-5 is formed inside the front end convex curved surface 3a-1. A thick portion 3a-6 is formed on the inside of 2.

When thick parts like this are created.

a. The weight of the spoiler increases.

The amount of b0 synthetic resin material used is large, and the material cost is high.

C1 When the molten synthetic resin solidifies, sink marks occur near the thick portion.

This causes problems such as:

The problem described in the conventional example shown in FIG.

In order to solve the problems described in the conventional example shown in FIG. 3 and to manufacture a spoiler without requiring joining work and therefore without requiring manual finishing of the joined parts, a well-known blow molding method is applied. It is also possible.

Blow molding method (Blow molding method)
g) is one of the molding methods for synthetic resin products having a hollow interior, and is applied to thermoplastic plastics, and is also called blow molding.

The steps involved are heating and melting, forming a softened tube (called a parison), expansion molding under gas pressure in a closed mold, cooling, and removing the molded product.

For molding parisons, there are injection methods, extrusion methods, and combination methods of both, all of which are known techniques, but the extrusion method is generally used.

For molding hollow doll products, the combination of the injection type and extrusion type described above is suitable.

The methods for blowing gas (air, for example) include the Brax method, which blows from above and below through a hollow mandrel that is coaxial with the die, and the Mils method, which blows by inserting a hollow needle into the parison shaft from a perpendicular direction.

A typical example is the Caudex method, in which a hollow mandrel is inserted from the bottom end of a vertical parison and blown into it. Other methods include a method in which a hollow needle is inserted into the parison shaft from the same direction, a method in which a U-shaped parison is extruded and a blowing tool is inserted from the open side of the parison, and the other end is fused and sealed with a split mold to inject gas; Alternatively, various methods have been developed and are known, such as a method in which a material that generates gas upon heating is dropped into the parison without blowing gas into it.

[Problem to be solved by the invention]

Exterior parts of vehicles (e.g. spoilers) by blow molding method
Compared to the conventional technology shown in Figs. 2 and 3, molding does not require joining operations, and therefore does not require manual finishing of the joints, but it does not require minute foreign matter to adhere to the surface of the molded product. The appearance will not be very good even if you paint over it, as it may cause roughness, roughness, and die lines (marks of the mating mold).

For this reason, surface polishing of the blow molded product is required.

Exterior parts for vehicles (e.g. spoilers) are curved.

Since it contains many curved surfaces, automatic polishing is not easy and manual polishing is required.

For example, polishing the surface of a blow-molded product using an air sander requires a great deal of time and effort, and the working environment is poor, requiring special consideration for the health management of workers.

The present invention was made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a blow molding method for manufacturing a blow molded product that can obtain a beautiful appearance even when painted without surface polishing. .

[Means to solve the problem]

In order to achieve the above object, the method of the present invention includes a method for blow molding a synthetic resin vehicle exterior part, in which a film made of a material that is compatible with the above synthetic resin is placed in a molding die. The film is heated by an infrared heater, the heated film is vacuum-adsorbed against a blow molding mold, and the parison is supplied into the blow molding mold for blow molding. Features.

[Effect]

According to the above-mentioned method, an integral molded product in which a sheet shaped along the surface of a blow-molded synthetic resin hollow member is welded to the surface is constructed in a simple process.

Since the surface is covered with a film, the surface is smooth, and even if painted without polishing, a beautiful appearance can be obtained, and the product value is high.

Moreover, if the above-mentioned film is coated in advance and then the molding operation is performed, the finished product can be obtained at the same time as the molding operation is completed.

〔Example〕

FIG. 1(A) is a schematic cross-sectional view showing an example of a spoiler forming apparatus configured to carry out the method of the present invention, and FIG. 1(B) is a perspective view thereof.

4A and 4B are molds, and mold mounting boards 5A and 5 are respectively
It is attached to B.

The mold 4A is provided with suction holes 6 for vacuum suction.

The suction hole 6 is connected to the vacuum tank 1 through a multi-channel passage 7, a vacuum pipe line 8, and a solenoid valve 9 provided in the mold mounting board 5A.
Connected to 0.

The inside of the vacuum tank lo is evacuated by a vacuum pump 11 to maintain a vacuum.

When the electromagnetic valve 9 is operated to the position (a) as shown in the figure, the vacuum suction hole 6 is communicated with the vacuum tank 1o and performs a vacuum suction action.

12 is a pressure gauge (vacuum needle).

When the solenoid valve 9 is operated to the position (b), the vacuum suction hole 6 is disconnected from the vacuum tank 1o and is opened to the atmosphere via the breather 13. As a result, the vacuum suction effect described above disappears.

A filter (not shown) is provided to prevent dust from being sucked into the breather 13.

14 is a die into which a molten thermoplastic synthetic resin material is fed, and a parison 15 is inserted between a pair of molds 4A and 4B.
supply.

Reference numeral 16 denotes a long film, which is made of a synthetic resin material having good compatibility with the synthetic resin constituting the parison 15.

The above-mentioned film 16 is wound around a roll shaft 17, stretched across the mold 4A, and taken up by a take-up shaft 18.

19 is a motor for driving the winding shaft 18.

Reference numeral 20 denotes a far-infrared heater, which is supported through the film 16 at a position facing the mold 4A, and is driven back and forth by a cylinder 21 as shown by the reciprocating arrow c-d, so that it does not interfere with the blow molding operation. It is possible to retreat to and return to a certain position.

Next, an example in which the blow molding method according to the present invention was carried out using the apparatus shown in FIG. 1 will be described.

The film 16 is fed out from the roll shaft 17 and transferred to the winding shaft 18.
The film 16 is wound up and stretched almost in contact with the mold 4A, and the film 16 is heated by the far-infrared heater 20.
Soften.

Operate the solenoid valve 9 to the (a) position to remove the film 16.
is vacuum suctioned by the vacuum suction hole 6.

The softened film 16 is adsorbed and molded into a shape that fits into the inner surface of the mold 4A.

The far infrared heater 20 is evacuated, the parison 15 is suspended from the die 14, and the pair of molds 4
The pair of molds 4A and 4B are closed by a drive device (not shown), and air is blown into the parison 15. When carrying out the present invention, the air (or gas) blowing method can be appropriately selected from any known methods.

As a result, the parison 15 becomes a hollow spoiler having the same outer contour as the cavity formed by the molds 4A and 4B, and is heat-sealed and integrated with the film 16.

When this is cooled and the mold is opened, a spoiler with a smooth surface is taken out.

Since the surface is smooth, a beautiful appearance can be obtained even when painted without polishing.

In addition, as an application example of the method of the present invention, the above-mentioned film 16
It is also possible to simplify the painting work after blow molding by applying a coating in advance.

For example, instead of three coats and one bake process, one coat and one bake process is now sufficient.

When carrying out the present invention, the synthetic resin material forming the parison 15 is selected to be one that provides the required strength and has good moldability, and the material forming the film 16 is compatible with the above-mentioned synthetic resin for the parison. Materials with good solubility and paintability can be selected.

In other words, even if the strength or blow moldability is poor, there will be no practical problem, so it is easy to select a material with good paintability.

〔Effect of the invention〕

As explained above, when blow molding vehicle exterior parts made of synthetic resin, the method of the present invention is applied to place a film made of a material that is compatible with the above synthetic resin against a molding die. Then, the above-mentioned film is heated with an infrared heater, the above-mentioned heated film is vacuum-adsorbed to a blow-molding mold, and the parison is supplied into the blow-molding mold and blow-molded.

It has the excellent practical effect of providing a beautiful appearance even when painted without surface polishing after blow molding, and can both improve the commercial value of car body exterior parts and reduce manufacturing costs.

[Brief explanation of drawings]

FIG. 1(A) is a schematic cross-sectional view showing an apparatus used in an embodiment of the method of the present invention. FIG. 1(B) is a schematic perspective view of the above device. FIGS. 2 and 3 are explanatory diagrams of conventional techniques, respectively. 4A, 4B... Mold, 5A, 5B... Mold mounting board, 6
・・Vacuum suction hole, 7・Multiple passages, 8・Vacuum suction pipe, 9 Solenoid valve, 10・Vacuum tank, 11・Vacuum pump, 12・Pressure gauge, 13・Breather, 14・・Die, 15, parison, 16... film, 20, far infrared heater.

Claims (1)

[Claims] 1. In a method for blow molding a vehicle exterior product made of synthetic resin, a film made of a material that is compatible with the synthetic resin described above is opposed to a mold, and an infrared heater is provided. for vehicles, characterized in that the above-mentioned film is heated, the above-mentioned heated film is vacuum-adsorbed to a blow-molding mold, and a parison is supplied into the blow-molding mold for blow molding. Blow molding method for exterior parts.